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Abstract:

The present invention is an electrophotographic photosensitive member
including a charge-transporting layer as the surface layer of the
electrophotographic photosensitive member having a matrix-domain
structure including: a matrix including a component β (at least one
resin of a polycarbonate resin C having a specific repeating structural
unit and a polyester resin D having a specific repeating structural
unit), and γ (charge-transporting substance having a specific
structure); and a domain including a component α (polycarbonate
resin A having a repeating structural unit containing a specific siloxane
moiety).

Claims:

1. An electrophotographic photosensitive member, comprising: a conductive
support, a charge-generating layer which is provided on the conductive
support and comprises a charge-generating substance, and a
charge-transporting layer which is provided on the charge-generating
layer and is a surface layer of the electrophotographic photosensitive
member; wherein the charge-transporting layer has a matrix-domain
structure having: a domain which comprises a polycarbonate resin A having
a repeating structural unit represented by the following formula (A) and
a repeating structural unit represented by the following formula (B); and
a matrix which comprises, at least one resin selected from the group
consisting of a polycarbonate resin C having a repeating structural unit
represented by the following formula (C) and a polyester resin D having a
repeating structural unit represented by the following formula (D), and
at least one charge-transporting substance selected from the group
consisting of a compound represented by the following formula (1) and a
compound represented by the following formula (1'); wherein the content
of a siloxane moiety in the polycarbonate resin A is not less than 5% by
mass and not more than 40% by mass relative to the total mass of the
polycarbonate resin A; ##STR00023## wherein, in the formula (A), "a"
represents number of repetitions of a structure within the bracket, an
average of "a" in the polycarbonate resin A ranges from 20 to 200;
##STR00024## wherein, in the formula (B), R21 to R24 each
independently represents a hydrogen atom, or a methyl group, and Y1
represents a single bond, a methylene group, an ethylidene group, a
propylidene group, a phenylethylidene group, a cyclohexylidene group, or
an oxygen atom; ##STR00025## wherein, in the formula (C), R31 to
R34 each independently represents a hydrogen atom, or a methyl
group, and Y2 represents a single bond, a methylene group, an
ethylidene group, a propylidene group, a phenylethylidene group, a
cyclohexylidene group, or an oxygen atom; ##STR00026## wherein, in the
formula (D), R41 to R44 each independently represents a
hydrogen atom, or a methyl group, X represents a meta-phenylene group, a
para-phenylene group, or a bivalent group having two para-phenylene
groups bonded via an oxygen atom, and Y3 represents a single bond, a
methylene group, an ethylidene group, a propylidene group, a
cyclohexylidene group, or an oxygen atom; ##STR00027## wherein, in the
formulae (1) and (1'), Ar1 represents a phenyl group, or a phenyl
group substituted with a methyl group or an ethyl group, Ar2
represents a phenyl group, a phenyl group substituted with a methyl
group, a phenyl group substituted with a univalent group representing the
formula "--CH═CH--Ta", or a biphenyl group substituted with a
univalent group represented by the formula "--CH═CH--Ta" (where, Ta
represents a univalent group derived from a benzene ring of a
triphenylamine by loss of one of the hydrogen atom, or derived from a
benzene ring of a triphenylamine substituted with a methyl group or an
ethyl group by loss of one of the hydrogen atom), R1 represents a
phenyl group, a phenyl group substituted with a methyl group, or a phenyl
group substituted with a univalent group represented by the formula
"--CH═(Ar3)Ar4" (where, Ar2 and Ar4 each
independently represents a phenyl group or a phenyl group substituted
with a methyl group), and R2 represents a hydrogen atom, a phenyl
group, or a phenyl group substituted with a methyl group.

2. An electrophotographic photosensitive member according to claim 1,
wherein the content of the siloxane moiety in the charge-transporting
layer is not less than 1% by mass and not more than 20% by mass relative
to the total mass of whole resins in the charge-transporting layer.

3. An electrophotographic photosensitive member according to claim 1,
wherein, in the formula (A), the average of "a" in the polycarbonate
resin A ranges from 30 to 100.

4. A process cartridge detachably attachable to a main body of an
electrophotographic apparatus, wherein the process cartridge integrally
supports: the electrophotographic photosensitive member according to
claim 1, and at least one device selected from the group consisting of a
charging device, a developing device, a transferring device, and a
cleaning device.

5. An electrophotographic apparatus, comprising: the electrophotographic
photosensitive member according to claim 1; a charging device; an
exposing device; a developing device; and a transferring device.

6. A method of manufacturing the electrophotographic photosensitive
member according to claim 1, wherein the method comprises a step of
forming the charge-transporting layer by applying a
charge-transporting-layer coating solution on the charge-generating
layer, and wherein the charge-transporting-layer coating solution
comprises: the polycarbonate resin A, at least one resin selected from
the group consisting of the polycarbonate resin C and the polyester resin
D, and at least one charge-transporting substance selected from the group
consisting of a compound represented by the formula (1) and a compound
represented by the formula (1').

Description:

TECHNICAL FIELD

[0001] The present invention relates to an electrophotographic
photosensitive member, a process cartridge, an electrophotographic
apparatus, and a method of manufacturing an electrophotographic
photosensitive member.

BACKGROUND ART

[0002] The electrophotographic photosensitive member mounted on
electrophotographic apparatuses includes organic electrophotographic
photosensitive members (hereinafter, referred to as an
"electrophotographic photosensitive member") containing an organic
charge-generating substance (organic photoconductive substance). In the
electrophotographic process, the surface of the electrophotographic
photosensitive member contacts a variety of objects such as a developer,
a charging member, a cleaning blade, paper, and a transfer member
(hereinafter, referred to as a "contacting member and the like"). For
this reason, there has been a demand for reduction in deterioration of
image quality caused by contact stress when the electrophotographic
photosensitive member contacts the contacting member and the like.
Particularly, recently, persistency of a reducing effect on deterioration
in image quality caused by the contact stress has been demanded of the
electrophotographic photosensitive member as the durability of the
electrophotographic photosensitive member is improved.

[0003] For continuous relaxation of the contact stress, PTL 1 proposes a
method in which using a siloxane resin having a siloxane structure
incorporated in the molecular chain, a matrix-domain structure is formed
in a surface layer. The disclosure shows that using a polyester resin
having a specific siloxane structure incorporated, continuous relaxation
of the contact stress can be compatible with potential stability
(suppression of fluctuation) when the photoreceptor is repeatedly used.

[0004] On the other hand, there has been a proposal that a siloxane
modified resin having a siloxane structure in the molecular chain is
added to the surface layer of the electrophotographic photosensitive
member. PTL 2 proposes an electrophotographic photosensitive member
containing a polycarbonate-siloxane copolymerized resin having a specific
siloxane structure incorporated, and reports that wear resistance and
contamination resistance are improved by introduction of the siloxane
structure.

[0008] In the electrophotographic photosensitive member disclosed in PTL
1, reduction in the continuous contact stress is compatible with the
potential stability in repeating use. As a further examination by the
present inventors, however, it was found out that the potential stability
in repeating use can be further improved in the case where a
charge-transporting substance having a specific structure is used as the
charge-transporting substance.

[0009] In the electrophotographic photosensitive member disclosed in PTL 2
and containing the resin having an incorporated siloxane structure, the
contamination resistance and wear resistance when the photoreceptor is
used are improved. The resin having an incorporated siloxane structure
and used in PTL 2 has a surface layer formed only with a resin containing
a siloxane structure having a crosslinking moiety as a resin component.
Accordingly, it was found out that in the resin having an incorporated
siloxane structure used in PTL 2, the continuous relaxation of the
contact stress is not compatible with the potential stability in
repeating use.

Solution to Problem

[0010] An object of the present invention is to provide an
electrophotographic photosensitive member including a specific
charge-transporting substance wherein continuous relaxation of contact
stress between the electrophotographic photosensitive member and a
contacting member and the like is highly compatible with potential
stability in repeating use. Another object of the present invention is to
provide a process cartridge having the electrophotographic photosensitive
member, and an electrophotographic apparatus. Yet another object of the
present invention is to provide a method of manufacturing the
electrophotographic photosensitive member.

[0011] The objects above are achieved by the present invention below.

[0012] The present invention relates to an electrophotographic
photosensitive member, comprising: a conductive support, a
charge-generating layer which is provided on the conductive support and
comprises a charge-generating substance, and a charge-transporting layer
which is provided on the charge-generating layer and is a surface layer
of the electrophotographic photosensitive member, wherein the
charge-transporting layer has a matrix-domain structure having; a domain
which comprises a polycarbonate resin A having a repeating structural
unit represented by the following formula (A) and a repeating structural
unit represented by the following formula (B); and a matrix which
comprises, at least one resin selected from the group consisting of a
polycarbonate resin C having a repeating structural unit represented by
the following formula (C) and a polyester resin D having a repeating
structural unit represented by the following formula (D), and at least
one charge-transporting substance selected from the group consisting of a
compound represented by the following formula (1) and a compound
represented by the following formula (1'), wherein the content of a
siloxane moiety in the polycarbonate resin A is not less than 5% by mass
and not more than 40% by mass relative to the total mass of the
polycarbonate resin A.

##STR00001##

wherein, in the formula (A), "a" represents the number of repetitions of
a structure within brackets, and an average of "a" in the polycarbonate
resin A ranges from 20 to 200;

##STR00002##

wherein, in the formula (B), R21 to R24 each independently
represent a hydrogen atom or a methyl group; Y1 represents a single
bond, a methylene group, an ethylidene group, a propylidene group, a
phenylethylidene group, a cyclohexylidene group, or an oxygen atom;

##STR00003##

wherein, in the formula (C), R31 to R34 each independently
represent a hydrogen atom or a methyl group; Y2 represents a single
bond, a methylene group, an ethylidene group, a propylidene group, a
phenylethylidene group, a cyclohexylidene group, or an oxygen atom;

##STR00004##

wherein, in the formula (D), R41 to R44 each independently
represent a hydrogen atom or a methyl group; X represents a
meta-phenylene group, a para-phenylene group, or a bivalent group having
two para-phenylene groups bonded via an oxygen atom; Y3 represents a
single bond, a methylene group, an ethylidene group, a propylidene group,
a cyclohexylidene group, or an oxygen atom;

##STR00005##

wherein, in the formulae (1) and (1'), Ar1 represents a phenyl group
or a phenyl group substituted with a methyl group or an ethyl group;
Ar2 represents a phenyl group, a phenyl group substituted with a
methyl group, a phenyl group substituted with a univalent group
represented by --CH═CH--Ta, or a biphenyl group substituted with a
univalent group represented by --CH═CH--Ta (wherein Ta represents a
univalent group derived from a benzene ring of a triphenylamine by loss
of one hydrogen atom, or a univalent group derived from a benzene ring of
a triphenylamine substituted with a methyl group or an ethyl group by
loss of one hydrogen atom); R1 represents a phenyl group, a phenyl
group substituted with a methyl group, or a phenyl group having a
univalent group substituted with --CH═C(Ar3)Ar4 (wherein
Ar3 and Ar4 each independently represent a phenyl group or a
phenyl group substituted with a methyl group); R2 represents a
hydrogen atom, a phenyl group, or a phenyl group substituted with a
methyl group.

[0013] The present invention also relates to a process cartridge
detachably attachable to a main body of an electrophotographic apparatus
wherein the process cartridge integrally supports the electrophotographic
photosensitive member and at least one device selected from the group
consisting of a charging device, a developing device, a transferring
device, and a cleaning device.

[0014] The present invention also relates to an electrophotographic
apparatus including the electrophotographic photosensitive member, a
charging device, an exposing device, a developing device, and a
transferring device.

[0015] The present invention also relates to a method of manufacturing the
electrophotographic photosensitive member wherein the method includes a
step of applying a coating solution for a charge-transporting layer
containing the polycarbonate resin A, at least one resin selected from
the group consisting of the polycarbonate resin C and the polyester resin
D, and at least one charge-transporting substance selected from the group
consisting of a compound represented by the formula (1) and a compound
represented by the formula (1') onto the charge-generating layer, and
drying the coating solution to form a charge-transporting layer.

Advantageous Effects of Invention

[0016] The present invention can provide an electrophotographic
photosensitive member including a specific charge-transporting substance
wherein continuous relaxation of contact stress between the
electrophotographic photosensitive member and a contacting member and the
like is highly compatible with potential stability in repeating use. The
present invention can also provide a process cartridge having the
electrophotographic photosensitive member, and an electrophotographic
apparatus. The present invention can also provide a method of
manufacturing the electrophotographic photosensitive member.

[0017] Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference to the
attached drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0018]FIG. 1 is a drawing illustrating an example of a schematic
configuration of an electrophotographic apparatus including a process
cartridge having an electrophotographic photosensitive member according
to the present invention.

DESCRIPTION OF EMBODIMENTS

[0019] Hereinafter, a polycarbonate resin A having the repeating
structural unit represented by the formula (A) and the repeating
structural unit represented by the formula (B) is referred to as a
component α. At least one resin selected from a polycarbonate resin
C having the repeating structural unit represented by the formula (C) and
a polyester resin D having the repeating structural unit represented by
the formula (D) is referred to as a component β. At least one
charge-transporting substance of compounds represented by the formulas
(1) and (1') is referred to as a component γ.

[0020] The electrophotographic photosensitive member according to the
present invention includes a conductive support, a charge-generating
layer provided on the conductive support, and a charge-transporting layer
which is provided on the charge-generating layer, and is a surface layer
of the electrophotographic photosensitive member, wherein the
charge-transporting layer has a matrix-domain structure having a matrix
including the components β and γ and a domain including the
component α, as described above.

[0021] In the matrix-domain structure in the present invention, the matrix
corresponds to a sea, and the domain corresponds to an island in a "sea
island structure." The domain including the component α represents
a granular (island-like) structure formed in the matrix including the
components β and γ. In the domain including the component
α, the domains independently exist in the matrix. Such a
matrix-domain structure can be recognized by observation of the surface
of the charge-transporting layer or the cross section of the
charge-transporting layer.

[0022] Observation of the state of the matrix-domain structure or
measurement of the domain can be performed using a commercially available
laser microscope, optical microscope, electron microscope, or atomic
force microscope, for example. Using the microscope, observation of the
state of the matrix-domain structure or measurement of the domain can be
performed at a predetermined magnification.

[0023] The number average particle size of the domain including the
component α in the present invention is preferably not less than
100 nm and not more than 1,000 nm. Narrower particle size distribution of
the particle size of each domain is preferable from the viewpoint of
persistency of a relaxing effect on the contact stress. The number
average particle size in the present invention is obtained as follows:
100 domains are arbitrarily selected from the domains observed by the
microscope in a vertical cross section of the charge-transporting layer
of the present invention. The largest diameters of the cut domains are
measured, and averaged to calculate the number average particle size of
the domain. By observation of the cross section of the
charge-transporting layer with the microscope, the image information in
the depth direction can be obtained, and a three-dimensional image of the
charge-transporting layer can be obtained.

[0024] In order to form the matrix-domain structure in the present
invention, the content of the siloxane moiety in the polycarbonate resin
A as the component α is preferably not less than 1% by mass and not
more than 20% by mass relative to the total mass of whole resins in the
charge-transporting layer. From the viewpoint of compatibility of the
continuous relaxation of the contact stress with the potential stability
in repeating use, the content of the siloxane moiety in the polycarbonate
resin A as the component α is also preferably not less than 1% by
mass and not more than 20% by mass relative to the total mass of the
whole resins in the charge-transporting layer. More preferably, at a
content of not less than 2% by mass and not more than 10% by mass, the
continuous relaxation of the contact stress and the potential stability
in repeating use can be further enhanced.

[0025] The matrix-domain structure of the charge-transporting layer of the
electrophotographic photosensitive member according to the present
invention can be formed using a coating solution for a
charge-transporting layer containing the components α, β and
γ. Then, the coating solution for a charge-transporting layer is
applied onto the charge-generating layer, and dried. Thereby, the
electrophotographic photosensitive member according to the present
invention can be manufactured.

[0026] The matrix-domain structure in the present invention is a structure
in which the domain including the component α is formed in the
matrix including the components β and γ. It is thought that
the domain including the component α is formed not only on the
surface of the charge-transporting layer but also inside of the
charge-transporting layer, and thereby the contact stress relaxation
effect is persistently demonstrated. Specifically, it is thought that the
siloxane resin component having the contact stress relaxation effect
reduced by friction with the member such as paper and the cleaning blade
can be supplied from the domains in the charge-transporting layer.

[0027] The present inventors found out that in the case where a specific
charge-transporting substance is used as the charge-transporting
substance, the potential stability in repeating use can be further
improved. Moreover, the present inventors presume the reason that the
potential stability in repeating use is further enhanced in the
electrophotographic photosensitive member according to the present
invention containing a specific charge-transporting substance (component
γ) as follows.

[0028] In the electrophotographic photosensitive member according to the
present invention having the charge-transporting layer having the
matrix-domain structure, in order to suppress the potential fluctuation
in repeating use, it is important to reduce the content of the
charge-transporting substance in the domain in the formed matrix-domain
structure as much as possible. In the case where the charge-transporting
substance has high compatibility with the resin that forms the domain and
has a siloxane structure incorporated, a larger amount of the
charge-transporting substance is contained in the domain, charges are
captured by the charge-transporting substance in the domain during
repeating use of the photoreceptor, leading to insufficient potential
stability.

[0029] In the electrophotographic photosensitive member including a
specific charge-transporting substance, improvement of properties is
necessary by a resin having a siloxane structure incorporated for
compatibility of the potential stability in repeating use with the
persistent relaxing effect on the contact stress. The component γ
in the present invention is a charge-transporting substance having high
compatibility with the resin in the charge-transporting layer, and it is
thought that the siloxane-containing resin undesirably contains a large
amount of component γ in the domain, and the component γ is
easily aggregated.

[0030] In the present invention, the domain including the component
α of the present invention is formed in the electrophotographic
photosensitive member including the component γ. Thereby, a high
charge-transporting ability can be kept. It is thought that the reason is
that formation of the domain including the component α reduces the
content of the component γ (specific charge-transporting substance)
in the domain. It is thought that the reason is that the siloxane
structure in the polycarbonate resin A as the component α can
reduce the component γ having a structure easily compatible with
the resin that remains in the domain.

<About Component γ>

[0031] The component γ in the present invention is at least one
charge-transporting substance selected from the compounds represented by
the following formulas (1) and (1'):

##STR00006##

wherein Ar1 represents a phenyl group, or a phenyl group substituted
with a methyl group or an ethyl group; Ar2 represents a phenyl
group, a phenyl group substituted with a methyl group, a phenyl group
substituted with a univalent group represented by --CH═CH--Ta, or a
biphenyl group substituted with a univalent group represented by
--CH═CH--Ta (wherein Ta represents a univalent group derived from a
benzene ring of a triphenylamine by loss of one hydrogen atom, or a
univalent group derived from a benzene ring of a triphenylamine
substituted with a methyl group or an ethyl group by loss of one hydrogen
atom); R1 represents a phenyl group, a phenyl group substituted with
a methyl group, or a phenyl group having a univalent group substituted
with --CH═C(Ar3)Ar4 (wherein Ar3 and Ar4 each
independently represent a phenyl group or a phenyl group substituted with
a methyl group); R2 represents a hydrogen atom, a phenyl group, or a
phenyl group substituted with a methyl group.

[0032] Hereinafter, specific examples of the component [γ], i.e.,
the charge-transporting substances represented by the above formulas (1)
and (1') will be shown:

##STR00007## ##STR00008##

[0033] Among these, the component γ is preferably a
charge-transporting substance having a structure represented by the above
formulas (1-1), (1-3), (1-5), and (1-7).

<About Component α>

[0034] The component α in the present invention is a polycarbonate
resin A having the repeating structural unit represented by the following
formula (A) and the repeating structural unit represented by the
following formula (B). The content of siloxane moiety in the
polycarbonate resin A is not less than 5% by mass and not more than 40%
by mass:

##STR00009##

wherein "a" represents the number of repetitions of a structure within
brackets, and an average of "a" in the polycarbonate resin A ranges from
20 to 200;

##STR00010##

wherein R21 to R24 each independently represent a hydrogen atom
or a methyl group; Y1 represents a single bond, a methylene group,
an ethylidene group, a propylidene group, a phenylethylidene group, a
cyclohexylidene group, or an oxygen atom.

[0035] Hereinafter, the component α, i.e., the polycarbonate resin A
having the above repeating structural unit represented by the formula (A)
and the above repeating structural unit represented by the formula (B)
will be described.

[0036] "a" in the above formula (A) represents the number of repetitions
of the structure within the brackets, and an average of "a" in the
polycarbonate resin A ranges from 20 to 200. More preferably, "a" is not
less than 30 and not more than 100 from the viewpoint of compatibility of
the continuous contact stress relaxation with the potential stability in
repeating use. Preferably, the number of repetitions "a" of the structure
within the brackets in each repeating structural unit is within the range
of ±10% of the value shown as the average of the number of repetitions
"a" because the effect of the present invention is stably obtained.

[0037] In Table 1, examples of the above repeating structural unit
represented by the formula (A) will be shown.

[0038] Among these, the repeating structural units represented by the
above formulas (A-1), (A-2), (A-3), (A-4), and (A-5) are preferable.

[0039] Next, the above repeating structural unit represented by the
formula (B) will be described. Hereinafter, specific examples of the
above repeating structural unit represented by the formula (B) will be
shown:

[0041] The polycarbonate resin A as the component α in the present
invention contains not less than 5% by mass and not more than 40% by mass
of a siloxane moiety relative to the total mass of the polycarbonate
resin A.

[0042] In the present invention, the siloxane moiety is a moiety including
silicon atoms on both ends that form a siloxane portion, a group boned to
the silicon atoms, an oxygen atom, a silicon atom, and a group bonded
thereto between the silicon atoms on the ends. Specifically, in the
present invention, the siloxane moiety refers to a moiety surrounded by
the dashed line below in the case of the repeating structural unit
represented by the following formula (A-S):

[0044] If the content of the siloxane moiety relative to the total mass of
the polycarbonate resin A as the component α in the present
invention is less than 5% by mass, a persistent reducing effect on the
contact stress cannot be sufficiently obtained, and the domain cannot be
efficiently formed in the matrix including the components β and
γ. If the content of the siloxane moiety is more than 40% by mass,
the component γ is aggregated in the domain including the component
α, and the potential stability in repeating use cannot be
sufficiently obtained.

[0045] The content of the siloxane moiety relative to the total mass of
the polycarbonate resin A as the component α in the present
invention can be analyzed by an ordinary analyzing method. Hereinafter,
an example of the analyzing method will be shown.

[0046] First, the charge-transporting layer as the surface layer of the
electrophotographic photosensitive member is dissolved by a solvent.
Subsequently, using an fractionating apparatus that can separate and
recover each composition component such as a size exclusion chromatograph
and a high performance liquid chromatograph, a variety of materials
contained in the charge-transporting layer as the surface layer are
fractionated. The fractionated polycarbonate resin A as the component
α is subjected to 1H-NMR measurement. Using a conversion
method using the peak position and the ratio of the peak area of the
hydrogen atom (hydrogen atom that forms the resin) obtained by the
1H-NMR measurement, the structure and content of the material that
forms the resin can be recognized. From those results, the number of
repetitions of the siloxane moiety and the molar ratio are calculated,
and converted into the content (mass ratio). Alternatively, the
fractionated polycarbonate resin A as the component α is hydrolyzed
in the presence of an alkali, and decomposed into a carboxylic acid
portion and a bisphenol portion. The obtained bisphenol portion is
subjected to nuclear magnetic resonance spectrum analysis or mass
spectrometry. The number of repetitions of the siloxane moiety and the
molar ratio are calculated, and converted into the content (mass ratio).

[0047] In the present invention, the mass ratio of the siloxane moiety
contained in the polycarbonate resin A as the component α was
measured using the method above.

[0048] The polycarbonate resin A as the component α used in the
present invention is a copolymer of the repeating structural unit
represented by the above formula (A) and the repeating structural unit
represented by the above formula (B). The form of copolymerization may be
any form such as block copolymerization, random copolymerization, and
alternating copolymerization.

[0049] The weight-average molecular weight of the polycarbonate resin A as
the component α used in the present invention is preferably not
less than 30,000 and not more than 150,000 from the viewpoint of
formation of the domain in the matrix containing the components β
and γ. The weight-average molecular weight is more preferably not
less than 40,000 and not more than 100,000.

[0050] In the present invention, the weight-average molecular weight of
the resin is a weight-average molecular weight in terms of polystyrene
measured by a method described in PTL 3 according to the standard method.

[0051] The polycarbonate resin A as the component α used in the
present invention can be synthesized by the conventional phosgene method,
for example. The polycarbonate resin A can also be synthesized by
transesterification.

[0052] Hereinafter, a synthesis example of the polycarbonate resin A as
the component α used in the present invention will be shown.

[0053] The polycarbonate resin A can be synthesized by a method described
in PTL 2. In the present invention, using the same synthesis method, the
component α (polycarbonate resin A) shown in Synthesis Example in
Table 2 was synthesized using materials corresponding to the above
repeating structural unit represented by the formula (A) and those
corresponding to the above repeating structural unit represented by the
formula (B). The weight-average molecular weight of the synthesized
polycarbonate resin A and the content of the siloxane moiety of the
polycarbonate resin A are shown in Table 2.

[0054] In the repeating structural unit example (A-1), the maximum number
of repetitions "a" within the brackets was 43, and the minimum number
thereof was 38. In the repeating structural unit example (A-6), the
maximum number of repetitions "a" within the brackets was 22, and the
minimum number thereof was 18. In the repeating structural unit example
(A-8), the maximum number of repetitions "a" within the brackets was 210,
and the minimum number thereof was 190.

<About Component β>

[0055] The component β in the present invention is at least one resin
selected from the polycarbonate resin C having the repeating structural
unit represented by the following formula (C) and the polyester resin D
having the repeating structural unit represented by the following formula
(D):

##STR00015##

wherein R31 to R34 each independently represent a hydrogen atom
or a methyl group; Y2 represents a single bond, a methylene group,
an ethylidene group, a propylidene group, a phenylethylidene group, a
cyclohexylidene group, or an oxygen atom;

##STR00016##

wherein R41 to R44 each independently represent a hydrogen atom
or a methyl group; X represents a meta-phenylene group, a para-phenylene
group, or a bivalent group having two para-phenylene groups bonded via an
oxygen atom; Y3 represents a single bond, a methylene group, an
ethylidene group, a propylidene group, a cyclohexylidene group, or an
oxygen atom.

[0056] Hereinafter, specific examples of the above repeating structural
unit represented by the formula (C) will be shown:

[0058] Hereinafter, specific examples of the above repeating structural
unit represented by the formula (D) will be shown:

##STR00019##

[0059] Among these, the repeating structural units represented by the
above formulas (D-1), (D-2), (D-6), and (D-7) are preferable. Preferably,
the β has no siloxane moiety from the viewpoint of formation of a
uniform matrix with the charge-transporting substance.

[0060] The charge-transporting layer as the surface layer of the
electrophotographic photosensitive member according to the present
invention contains the components α and β as the resins, and
another resin may be additionally mixed and used. Examples of the another
resin that may be mixed and used include acrylic resins, polyester
resins, and polycarbonate resins. In the case where another resin is
mixed and used, the proportion of the component β to the another
resin is preferably in the range of not less than 90% by mass to less
than 100% by mass. In the present invention, in the case where another
resin is mixed and used in addition to the component β (the
polycarbonate resin C or the polyester resin D), a resin having no
siloxane structure is preferably used as the another resin from the
viewpoint of formation of a uniform matrix with the charge-transporting
substance.

[0061] The charge-transporting layer as the surface layer of the
electrophotographic photosensitive member according to the present
invention contains the component γ as the charge-transporting
substance, and may contain a charge-transporting substance having a
different structure. Examples of the charge-transporting substance having
a different structure that may be contained include triarylamine
compounds and hydrazone compounds. Among these, use of the triarylamine
compounds as the charge-transporting substance is preferable from the
viewpoint of the potential stability in repeating use. In the case where
the charge-transporting substance other than the component γ is
mixed and used, not less than 50% by mass of the component γ is
preferably contained in all the charge-transporting substances contained
in the charge-transporting layer. More preferably, not less than 70% by
mass of the component γ is contained.

[0062] Next, a configuration of the electrophotographic photosensitive
member according to the present invention will be described.

[0063] The electrophotographic photosensitive member according to the
present invention is an electrophotographic photosensitive member
including a conductive support, a charge-generating layer provided on the
conductive support, and a charge-transporting layer provided on the
charge-generating layer. In the electrophotographic photosensitive
member, the charge-transporting layer is the surface layer (topmost
layer) of the electrophotographic photosensitive member.

[0064] The charge-transporting layer of the electrophotographic
photosensitive member according to the present invention contains the
components α, β and γ.

[0065] The charge-transporting layer may have a laminate structure. In
this case, at least the charge-transporting layer on the topmost surface
side has the matrix-domain structure.

[0066] As the electrophotographic photosensitive member, usually, a
cylindrical electrophotographic photosensitive member obtained by forming
a photosensitive layer (charge-generating layer, charge-transporting
layer) on a cylindrical conductive support is widely used; a belt-like or
sheet-like electrophotographic photosensitive member can be used.

[Conductive Support]

[0067] As the conductive support used in the present invention, those
having conductivity (conductive support) are preferable, and examples
thereof include aluminum and aluminum alloys. In the case of an aluminum
or aluminum alloy conductive support, an ED tube, an EI tube, and those
subjected to machining, electrochemical mechanical polishing, and wet or
dry honing can be used. Examples of the conductive support also include
those having a thin film of a conductive material such as aluminum,
aluminum alloys, or indium oxide-tin oxide alloys on a metallic
conductive support or a resin conductive support.

[0068] In order to suppress interference fringes, the surface of the
conductive support is preferably roughened properly. Specifically,
preferable is use of a conductive support whose surface is subjected to
honing, blasting, machining, or electropolishing or an aluminum or
aluminum alloy conductive support having a conductive layer containing a
conductive metal-oxide particle and a resin on the conductive support. In
order to suppress interference fringes produced in an output image by
interference of the light reflected on the conductive layer surface, a
surface roughening material for roughening the surface of the conductive
layer can be added.

[0069] In the electrophotographic photosensitive member according to the
present invention, a conductive layer having a conductive particle and a
resin may be provided on the conductive support. By a method for forming
the conductive layer having a conductive particle and a resin on the
conductive support, a powder containing a conductive particle in the
conductive layer is contained. Examples of the conductive particle
include carbon black, acetylene black, powders of metals such as
aluminum, nickel, iron, nichrome, copper, zinc, silver, and powders of
metal oxides such as conductive tin oxide and ITO.

[0070] Examples of the resin used for the conductive layer include
polyester resins, polycarbonate resins, polyvinyl butyral resins, acrylic
resins, silicone resins, epoxy resins, melamine resins, urethane resins,
phenol resins, and alkyd resins. These resins may be used alone, or two
or more thereof may be used in combination.

[0071] The conductive layer can be formed by dip coating or solvent
coating by a Meyer bar. Examples of a solvent for a coating solution for
a conductive layer include ether solvents, alcohol solvents, ketone
solvents, and aromatic hydrocarbon solvents.

[0072] The film thickness of the conductive layer is preferably not less
than 0.2 μm and not more than 40 μm, more preferably not less than
1 μm and not more than 35 μm, and still more preferably not less
than 5 μm and not more than 30 μm.

[Intermediate Layer]

[0073] In the electrophotographic photosensitive member according to the
present invention, an intermediate layer may be provided between the
conductive support or conductive layer and the charge-generating layer.

[0074] The intermediate layer can be formed as follows: a coating solution
for an intermediate layer containing a resin is applied onto the
conductive layer, and dried or cured.

[0075] Examples of the resin used for the intermediate layer include
polyacrylic acids, methyl cellulose, ethyl cellulose, polyamide resins,
polyimide resins, polyamideimide resins, polyamic acid resins, melamine
resins, epoxy resins, and polyurethane resins. As the resin used for the
intermediate layer, the thermoplastic resins are preferable, and the
thermoplastic polyamide resins are preferable. As the polyamide resin,
preferable are low crystalline or non-crystalline copolymerized nylons
that can be applied in a solution state.

[0076] The film thickness of the intermediate layer is preferably not less
than 0.05 μm and not more than 40 μm, and more preferably not less
than 0.1 μm and not more than 7 μm.

[0077] The intermediate layer may contain a semi-conductive particle, an
electron-transporting substance, or an electron receptive substance.

[Charge-Generating Layer]

[0078] In the electrophotographic photosensitive member according to the
present invention, a charge-generating layer is provided on the
conductive support, the conductive layer, or the intermediate layer.

[0079] Examples of the charge-generating substance used for the
electrophotographic photosensitive member according to the present
invention include azo pigments, phthalocyanine pigments, indigo pigments,
and perylene pigments. One or two or more of these charge-generating
substances may be used. Among these, particularly preferable are
oxytitanium phthalocyanine, hydroxy gallium phthalocyanine, and
chlorogallium phthalocyanine for their high sensitivity.

[0080] Examples of the resin used for the charge-generating layer include
polycarbonate resins, polyester resins, butyral resins, polyvinyl acetal
resins, acrylic resins, vinyl acetate resins, and urea resins. Among
these, butyral resins are particularly preferable. These can be used
alone, or two or more thereof can be mixed, or used as a copolymer.

[0081] The charge-generating layer can be formed as follows: a coating
solution for a charge-generating layer obtained by dispersing the
charge-generating substance, the resin, and a solvent is applied, and
dried. The charge-generating layer may be a deposited film of the
charge-generating substance.

[0082] Examples of a dispersion method include methods using a
homogenizer, an ultrasonic wave, a ball mill, a sand mill, an Attritor,
and a roll mill.

[0083] As the proportion of the charge-generating substance to the resin,
the charge-generating substance is preferably not less than 0.1 parts by
mass and not more than 10 parts by mass, and particularly more preferably
not less than 1 part by mass and not more than 3 parts by mass based on 1
part by mass of the resin.

[0084] Examples of the solvent used for the coating solution for a
charge-generating layer include alcohol solvents, sulfoxide solvents,
ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon
solvents.

[0085] The film thickness of the charge-generating layer is preferably not
less than 0.01 μm and not more than 5 μm, and more preferably not
less than 0.1 μm and not more than 2 μm.

[0086] A variety of sensitizers, antioxidants, ultraviolet absorbing
agents, and plasticizers can be added to the charge-generating layer when
necessary. In order to prevent clogging of a flow of charges in the
charge-generating layer, the charge-generating layer may contain an
electron transport substance or an electron receptive substance.

[Charge-Transporting Layer]

[0087] In the electrophotographic photosensitive member according to the
present invention, a charge-transporting layer is provided on the
charge-generating layer. The charge-transporting layer as the surface
layer of the electrophotographic photosensitive member according to the
present invention contains the component γ as the specific
charge-transporting substance, and may contain a charge-transporting
substance having a different structure as described above. The
charge-transporting substance having a different structure that may be
mixed is as described above.

[0088] The charge-transporting layer as the surface layer of the
electrophotographic photosensitive member according to the present
invention contains the components α and β as the resin, and as
described above, another resin may be mixed and used. The another resin
that may be mixed and used is as described above.

[0089] The charge-transporting layer can be formed as follows: a coating
solution for a charge-transporting layer obtained by dissolving the
charge-transporting substance and the respective resins in a solvent is
applied, and dried.

[0090] As the proportion of the charge-transporting substance to the
resin, the charge-transporting substance is preferably not less than 0.4
parts by mass and not more than 2 parts by mass, and more preferably not
less than 0.5 parts by mass and not more than 1.2 parts by mass based on
1 part by mass of the resin.

[0091] Examples of the solvent used for the coating solution for a
charge-transporting layer include ketone solvents, ester solvents, ether
solvents, and aromatic hydrocarbon solvents. These solvents may be used
alone, or two or more thereof may be mixed and used. Among these
solvents, use of ether solvents or aromatic hydrocarbon solvents is
preferable from the viewpoint of solubility of the resin.

[0092] The film thickness of the charge-transporting layer is preferably
not less than 5 μm and not more than 50 μm, and more preferably not
less than 10 μm and not more than 35 μm.

[0093] An antioxidant, an ultraviolet absorbing agent, a plasticizer, and
the like can be added to the charge-transporting layer when necessary.

[0094] A variety of additives can be added to the respective layers of the
electrophotographic photosensitive member according to the present
invention. Examples of the additives include deterioration preventing
agents such as an antioxidant, an ultraviolet absorbing agent, a light
stabilizer, and fine particles such as organic fine particles and
inorganic fine particles. Examples of the deterioration preventing agents
include hindered phenol antioxidants, hindered amine light stabilizers,
sulfur atom-containing antioxidants, and phosphorus atom-containing
antioxidants. Examples of the organic fine particles include polymer
resin particles such as fluorine atom-containing resin particles,
polystyrene fine particles, and polyethylene resin particles. Examples of
the inorganic fine particles include metal oxides such as silica and
alumina.

[0095] In application of the coating solution for each layer, coating
methods such as dip coating (immersion coating), spray coating, spin
coating, roller coating, Meyer bar coating, and blade coating can be
used.

[Electrophotographic Apparatus]

[0096]FIG. 1 shows an example of a schematic configuration of an
electrophotographic apparatus including a process cartridge having the
electrophotographic photosensitive member according to the present
invention.

[0097] In FIG. 1, a cylindrical electrophotographic photosensitive member
1 is rotated and driven around a shaft 2 in the arrow direction at a
predetermined circumferential speed. The surface of the rotated and
driven electrophotographic photosensitive member 1 is uniformly charged
at a negative predetermined potential by a charging device 3 (such as a
primary charging device: a charging roller) in a rotation process. Next,
the surface of the electrophotographic photosensitive member 1 receives
exposure light 4 (image exposure light) whose intensity is modulated
according to a chronological electrical digital image signal of the
information of a target image to be output from an exposing device such
as slit exposure and laser beam scanning exposure (not shown). Thus, an
electrostatic latent image corresponding to the information of the target
image is sequentially formed on the surface of the electrophotographic
photosensitive member 1.

[0098] The electrostatic latent image formed on the surface of the
electrophotographic photosensitive member 1 is developed by reversal
development using a toner contained in a developer in a developing device
5. Thus, a toner image is formed. Next, the toner image formed and
carried on the surface of the electrophotographic photosensitive member 1
is sequentially transferred by the transfer bias from a transferring
device 6 (such as a transfer roller) onto a transfer material P (such as
paper). The transfer material P is extracted from a transfer material
feeding device (not shown) in synchronization with rotation of the
electrophotographic photosensitive member 1, and fed between the
electrophotographic photosensitive member 1 and the transferring device
6. A bias voltage having a polarity opposite to that the toner has is
applied to the transferring device 6 from a bias power supply (not
shown).

[0099] The transfer material P having the transferred toner image thereon
is separated from the surface of the electrophotographic photosensitive
member 1, and conveyed to a fixing device 8. There, the toner image is
fixed. Then, the transfer material P is conveyed to outside of the
apparatus as an image formed product (print, copy).

[0100] The surface of the electrophotographic photosensitive member 1
after toner image transfer is cleaned by a cleaning device 7 (such as a
cleaning blade) by removing a transfer remaining developer (transfer
remaining toner). Next, the surface of the electrophotographic
photosensitive member 1 is discharged by the exposure light (not shown)
from the exposing device (not shown), and repeatedly used to form an
image. As shown in FIG. 1, the exposure is not always necessary if the
charging device 3 is a contact charging device using a charging roller.

[0101] In the present invention, several components are selected from the
electrophotographic photosensitive member 1, the charging device 3, the
developing device 5, the transferring device 6 and the cleaning device 7,
and the selected components may be accommodated in a container and
integrally supported as a process cartridge. Moreover, the process
cartridge may be configured to be detachably attached to the main body of
the electrophotographic apparatus such as a copier and a laser beam
printer. In FIG. 1, the electrophotographic photosensitive member 1, the
charging device 3, the developing device 5 and the cleaning device 7 are
integrally supported to form a cartridge, and the obtained process
cartridge 9 is detachably attached to the main body of the
electrophotographic apparatus using a guiding device 10 such as a rail in
the main body of the electrophotographic apparatus.

EXAMPLES

[0102] Hereinafter, the present invention will be described more in detail
using Examples and Comparative Examples. The present invention, however,
will not be limited to Examples below. "Parts" in Examples means "parts
by mass."

Example 1

[0103] An aluminum cylinder having a diameter of 30 mm and a length of
260.5 mm was used as a conductive support. Next, a coating solution for a
conductive layer was prepared using 10 parts of SnO2-coated barium
sulfate (conductive particle), 2 parts of titanium oxide (pigment for
adjusting resistance), 6 parts of a phenol resin, 0.001 parts of silicone
oil (leveling agent), and a mixed solvent of 4 parts of methanol and 16
parts of methoxypropanol. The coating solution for a conductive layer was
applied onto the aluminum cylinder by dip coating, and thermally cured at
140° C. for 30 minutes to form a conductive layer having a film
thickness of 15 μm.

[0104] Next, 3 parts of N-methoxymethylated nylon and 3 parts of a
copolymerized nylon were dissolved in a mixed solvent of 65 parts of
methanol and 30 parts of n-butanol to prepare a coating solution for an
intermediate layer.

[0105] The coating solution for an intermediate layer was applied onto the
conductive layer by dip coating, and dried at 100° C. for 10
minutes to form an intermediate layer having a film thickness of 0.7
μm.

[0106] Next, 10 parts of hydroxy gallium phthalocyanine (charge-generating
substance) in crystals having strong peaks at Bragg angles
(2θ±0.2°) of 7.5°, 9.9°, 16.3°,
18.6°, 25.1°, and 28.3° in CuKα properties X
ray diffraction was prepared. To this, 250 parts of cyclohexanone and 5
parts of a polyvinyl butyral resin (trade name: S-LEC BX-1, made by
Sekisui Chemical Co., Ltd.) was added. The mixed solution was dispersed
under a 23±3° C. atmosphere for 1 hour by a sand mill using
glass beads having a diameter of 1 mm. After dispersion, 250 parts of
ethyl acetate was added to prepare a coating solution for a
charge-generating layer. The coating solution for a charge-generating
layer was applied onto the intermediate layer by dip coating, and dried
at 100° C. for 10 minutes to form a charge-generating layer having
a film thickness of 0.26 μm.

[0107] Next, 10 parts of the charge-transporting substance having a
structure represented by the above formula (1-1) as the component
γ, 4 parts of the polycarbonate resin A(1) synthesized in Synthesis
Example 1 as the component α, and 6 parts of the polycarbonate
resin C (weight-average molecular weight of 120,000) containing the
repeating structure represented by the above formula (C-5) and the
repeating structure represented by (C-7) in the ratio of 8:2 as the
component β were dissolved in a mixed solvent of 20 parts of
tetrahydrofuran and 60 parts of toluene to prepare a coating solution for
a charge-transporting layer.

[0108] The coating solution for a charge-transporting layer was applied
onto the charge-generating layer by dip coating, and dried at 110°
C. for 1 hour to form a charge-transporting layer having a film thickness
of 16 μm. It was found that the formed charge-transporting layer
contains the domain including the component α in the matrix
including the components β and γ.

[0109] Thus, an electrophotographic photosensitive member having the
charge-transporting layer as the surface layer was produced. The
components α, β, and γ contained in the
charge-transporting layer, the content of the siloxane moiety (siloxane
content A) in the polycarbonate resin A, and the content of the siloxane
moiety (siloxane content B) in the polycarbonate resin A based on the
total mass of all the resins are shown in Table 3.

[0110] Next, evaluation will be described.

[0111] Evaluation was made about fluctuation of a bright potential
(potential fluctuation) when 2,000 sheets were repeatedly output, a
relative value of an initial torque, a relative value of the torque when
2,000 sheets were repeatedly output, and observation of the surface of
the electrophotographic photosensitive member at the time of measuring
the torque.

[0112] As an evaluation apparatus, a laser beam printer LBP-2510 made by
Canon Inc. was modified such that a charged potential (dark potential) of
the electrophotographic photosensitive member might be adjusted, and
used. A cleaning blade of a polyurethane rubber was set so as to have a
contact angle of 22.5° and a contact pressure of 35 g/cm to the
surface of the electrophotographic photosensitive member. Evaluation was
made under an environment at a temperature of 23° C. and a
relative humidity of 50%.

<Evaluation of Potential Fluctuation>

[0113] The exposure amount (image exposure amount) of the laser light
source at 780 nm in the evaluation apparatus was set such that the light
amount on the surface of the electrophotographic photosensitive member
might be 0.3 μJ/cm2. The potentials of the surface of the
electrophotographic photosensitive member (dark potential and bright
potential) were measured at the position of the developing device while
the developing device was replaced by a jig fixed such that a probe for
measuring a potential might be located 130 mm from the end of the
electrophotographic photosensitive member. The dark potential of a
non-exposed portion of the electrophotographic photosensitive member was
set at -450 V, and the bright potential photo-induced discharged from the
dark potential by irradiation with laser light was measured. Using a
plain paper of an A4 size, 2,000 sheets of an image were continuously
output. The fluctuation amounts of the bright potential before and after
the output were evaluated. A test chart having a printing ratio of 5% was
used. The result is shown in the Potential fluctuation of Table 8.

<Evaluation of Relative Value of Torque>

[0114] On the same condition as the evaluation condition of the potential
fluctuation, the driving current value (current value A) of a rotating
motor for the electrophotographic photosensitive member was measured. In
the evaluation, the amount of contact stress between the
electrophotographic photosensitive member and the cleaning blade was
evaluated. The obtained current value indicates the amount of the contact
stress between the electrophotographic photosensitive member and the
cleaning blade.

[0115] Further, an electrophotographic photosensitive member for comparing
the relative value of the torque was produced by the following method. An
electrophotographic photosensitive member was produced in the same manner
as in Example 1 except that the polycarbonate resin A(1) as the component
α used for the charge-transporting layer of the electrophotographic
photosensitive member in Example 1 was replaced by the component β
in Table 3, and only the component β was used as the resin. The
electrophotographic photosensitive member was used as the
electrophotographic photosensitive member for comparison.

[0116] Using the produced electrophotographic photosensitive member for
comparison, the driving current value (current value B) of the rotating
motor for the electrophotographic photosensitive member was measured in
the same manner as in Example 1.

[0117] The ratio of the driving current value (current value A) of the
electrophotographic photosensitive member containing the component
α according to the present invention to the driving current value
(current value B) of the rotating motor for the electrophotographic
photosensitive member without the component α was calculated. The
obtained numeric value of (current value A)/(current value B) was
compared as the relative value of the torque. The numeric value of the
relative value of the torque indicates a degree of reduction in the
amount of the contact stress between the electrophotographic
photosensitive member using the component α and the cleaning blade.
As the numeric value of the relative value of the torque is smaller, the
degree of reduction in the amount of the contact stress between the
electrophotographic photosensitive member and the cleaning blade is
higher. The result is shown in the Relative value of initial torque of
Table 8.

[0118] Subsequently, using a plain paper of an A4 size, 2,000 sheets of an
image were continuously output. A test chart having a printing ratio of
5% was used. Then, the relative value of the torque after 2,000 sheets
were repeatedly output was measured. The relative value of the torque
after 2,000 sheets were repeatedly output was evaluated in the same
manner as in the case of the relative value of the initial torque. In
this case, 2,000 sheets were repeatedly output also in the
electrophotographic photosensitive member for comparison, and the
relative value of the torque after 2,000 sheets were repeatedly output
was calculated using the driving current value of the rotating motor at
that time. The result is shown in the Relative value of torque after
2,000 sheets were repeatedly output in Table 8.

<Evaluation of Matrix-Domain Structure>

[0119] In the electrophotographic photosensitive member produced by the
method, a vertical cross section of the charge-transporting layer was
observed using an ultra-high depth shape measurement microscope VK-9500
(made by Keyence Corporation). At that time, at a magnification of an
object lens of 50 times, a field of a 100-μm square (10,000
μm2) of the surface of the electrophotographic photosensitive
member was observed, the largest diameters of 100 formed domains selected
at random in the visual field were measured. From the largest diameters,
the average was calculated, and defined as a number average particle
size. The results are shown in Table 8.

Examples 2 to 39

[0120] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the components α, β,
and γ of the charge-transporting layer in Example 1 were replaced
as shown in Table 3, and evaluated. It was found that in the formed
charge-transporting layer, the domain including the component α is
contained in the matrix including the components β and γ. The
result is shown in Table 8.

[0121] The weight-average molecular weight of the polycarbonate resin C
used as the component β was as follows:

(C-5)/(C-7)=8/2: 120,000

(C-1): 100,000.

Examples 40 to 78

[0122] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the components α, β
and γ of the charge-transporting layer in Example 1 were replaced
as shown in Table 4, and evaluated. It was found that in the formed
charge-transporting layer, the domain including the component α is
contained in the matrix including the components β and γ. The
result is shown in Table 8.

[0123] The weight-average molecular weight of the polycarbonate resin C
used as the component β was as follows:

(C-5)/(C-7)=8/2: 120,000

(C-2): 130,000

(C-3)/(C-5)=3/7: 100,000.

Examples 79 to 117

[0124] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the components α, β
and γ of the charge-transporting layer in Example 1 were replaced
as shown in Table 5, and evaluated. It was found that in the formed
charge-transporting layer, the domain including the component α is
contained in the matrix including the components β and γ. The
result is shown in Table 9.

[0125] The weight-average molecular weight of the polycarbonate resin C
used as the component β was as follows:

(C-6)/(C-7)=8/2: 120,000

(C-1)/(C-10)=7/3: 130,000

(C-1)/(C-4)=8/2: 120,000

(C-1)/(C-8)=8/2: 100,000

(C-1)/(C-9)=8/2: 90,000.

Examples 118 to 156

[0126] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the components α, β
and γ of the charge-transporting layer in Example 1 were replaced
as shown in Table 6, and evaluated. It was found that in the formed
charge-transporting layer, the domain including the component α is
contained in the matrix including the components β and γ. The
result is shown in Table 9. As the charge-transporting substance other
than the component γ, a charge-transporting substance having the
structure represented by the following formula (2-1) and the structure
represented by the following formula (2-2) was mixed with a
charge-transporting substance having a structure represented by the above
formula (1) or the above formula (1') as the component γ, and used:

##STR00020##

[0127] The weight-average molecular weight of the polyester resin D used
as the component β was as follows:

(D-1): 120,000

(D-2): 90,000

(D-1)/(D-4)=7/3: 130,000

(D-2)/(D-3)=9/1: 100,000

(D-5): 100,000

(D-7): 110,000.

[0128] The repeating structural units represented by the above formulas
(D-1), (D-2), (D-3), (D-4), and (D-5) each have the ratio of terephthalic
acid/isophthalic acid of 1/1.

Comparative Examples 1 to 12

[0129] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by polycarbonate resin (E(1): weight-average
molecular weight of 60,000) containing the repeating structural unit
represented by the above formula (A-1) and the repeating structural unit
represented by the above formula (B-1) and having the content of the
siloxane moiety of 2% by mass in a carbonate resin, and other changes
were made as shown in Table 7. The configuration of the resins contained
in the charge-transporting layer and the content of the siloxane moiety
are shown in Table 7. Evaluation was made in the same manner as in
Example 1. The result is shown in Table 10. It was found that the formed
charge-transporting layer has no matrix-domain structure.

Comparative Example 13

[0130] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that unlike Example 1, only the
polycarbonate resin E(1) was contained as the resin contained in the
charge-transporting layer. The configuration of the resins contained in
the charge-transporting layer and the content of the siloxane moiety are
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. It was found that the formed
charge-transporting layer has no matrix-domain structure. As the
electrophotographic photosensitive member for comparing the relative
value of the torque, the electrophotographic photosensitive member for
comparison used in Example 1 was used.

Comparative Examples 14 to 25

[0131] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by the polycarbonate resin (E(2): weight-average
molecular weight of 70,000) containing the repeating structural unit
represented by the above formula (A-1) and the repeating structural unit
represented by the above formula (B-1) and having the content of the
siloxane moiety of 50% by mass in the polycarbonate resin, and other
changes were made as shown in Table 7. The configuration of the resins
contained in the charge-transporting layer and the content of the
siloxane moiety are shown in Table 7. Evaluation was made in the same
manner as in Example 1. The result is shown in Table 10. In the
charge-transporting layer, the matrix-domain structure was formed.

Comparative Example 26

[0132] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that unlike Example 1, only the
polycarbonate resin E(2) was contained as the resins contained in the
charge-transporting layer. The configuration of the resins contained in
the charge-transporting layer and the content of the siloxane moiety are
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. It was found that the formed
charge-transporting layer has no matrix-domain structure. As the
electrophotographic photosensitive member for comparing the relative
value of the torque, the electrophotographic photosensitive member for
comparison used in Example 1 was used.

Comparative Example 27

[0133] The polycarbonate resin A(1) in Example 1 was replaced by the resin
E(3) including the repeating structure described in PTL 2. The resin E(3)
(weight-average molecular weight of 120,000) is a resin containing the
repeating structural unit represented by the following formula (E-3) and
the repeating structural unit represented by the above formula (B-5) in a
ratio of 10/90. The content of the siloxane moiety in the resin was 7% by
mass. A coating solution for a charge-transporting layer was prepared as
follows: 9 parts of the charge-transporting substance having the
structure represented by the above formula (1-1) as the component
γ, 6 parts of the polycarbonate resin E(3), and 1.2 parts of
1,4-bis(dimethylsilyl)benzene were dissolved in a mixed solvent of 20
parts of tetrahydrofuran and 60 parts of toluene; to this, 0.04 parts of
a platinum-cyclovinylmethylsiloxane complex (cyclovinylmethylsiloxane
solution containing 3 to 3.5% by weight of platinum atoms) was added as a
catalyst. The coating solution for a charge-transporting layer was
applied onto the charge-generating layer by dip coating, dried at
120° C. for 2 hours, and subsequently dried under the condition of
1 mmHg for 12 hours. Thereby, a charge-transporting layer including the
charge-transporting substance and the crosslinked polycarbonate resin and
having a film thickness of 16 μm was formed. Other than this, an
electrophotographic photosensitive member was produced in the same manner
as in Example 1. The configuration of the resins contained in the
charge-transporting layer and the content of the siloxane moiety are
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. It was found that the formed
charge-transporting layer has no matrix-domain structure. The numeric
value of the number of repetitions of the siloxane moiety in the
repeating structural unit represented by the following formula (E-3)
indicates the average of the number of repetitions. In this case, the
average of the number of repetitions of the siloxane moiety is 25 and 10
in the repeating structural unit represented by the following formula
(E-3) in the resin E(3):

##STR00021##

Comparative Example 28

[0134] An electrophotographic photosensitive member was produced in the
same manner as in Comparative Example 27 except that changes were made in
Comparative Example 27 as shown in Table 7. The configuration of the
resins contained in the charge-transporting layer and the content of the
siloxane moiety are shown in Table 7. Evaluation was made in the same
manner as in Example 1. The result is shown in Table 10. It was found
that the formed charge-transporting layer has no matrix-domain structure.

Comparative Examples 29 to 34

[0135] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by the resin E(4) (weight-average molecular weight
of 60,000) containing the repeating structural unit having the structure
described in PTL 1, i.e., represented by the following formula (E-4) and
the repeating structural unit represented by the above formula (D-1), and
having the content of the siloxane moiety of 30% by mass in the resin,
and other changes were made as shown in Table 7. The repeating structural
unit represented by the following formula (E-4) and that represented by
the above formula (D-1) have a ratio of terephthalic acid/isophthalic
acid skeleton of 1/1. The configuration of the resins contained in the
charge-transporting layer and the content of the siloxane moiety are
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. In the formed charge-transporting layer,
the matrix-domain structure was formed. As the electrophotographic
photosensitive member for comparing the relative value of the torque, the
electrophotographic photosensitive member for comparison used in Example
121 was used. The numeric value of the number of repetitions of the
siloxane moiety in the repeating structural unit represented by the
following formula (E-4) indicates the average of the number of
repetitions. In this case, the average of the number of repetitions of
the siloxane moiety is 40 in the repeating structural unit represented by
the following formula (E-4) in the resin E(4):

##STR00022##

Comparative Examples 35 to 38

[0136] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by the resin E(4), the charge-transporting
substance was replaced by that having the structure represented by the
above formula (2-1), and other changes were made as shown in Table 7. The
configuration of the resins contained in the charge-transporting layer
and the content of the siloxane moiety are shown in Table 7. Evaluation
was made in the same manner as in Example 1. The result is shown in Table
10. In the formed charge-transporting layer, the matrix-domain structure
was formed. As the electrophotographic photosensitive member for
comparing the relative value of the torque, the electrophotographic
photosensitive member for comparison used in Example 121 was used.

Comparative Examples 39 and 40

[0137] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by the polycarbonate resin A(2), the
charge-transporting substance was replaced by that having the structure
represented by the above formula (2-1), and other changes were made as
shown in Table 7. The configuration of the resins contained in the
charge-transporting layer and the content of the siloxane moiety are
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. In the formed charge-transporting layer,
the matrix-domain structure was formed. As the electrophotographic
photosensitive member for comparing the relative value of the torque, the
electrophotographic photosensitive member for comparison used in Example
121 was used.

Comparative Examples 41 to 46

[0138] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that the polycarbonate resin A(1) in
Example 1 was replaced by the resin E(3), and other changes were made as
shown in Table 7. Evaluation was made in the same manner as in Example 1.
The result is shown in Table 10. In the formed charge-transporting layer,
the matrix-domain structure was formed.

Comparative Example 47

[0139] An electrophotographic photosensitive member was produced in the
same manner as in Example 1 except that only the polycarbonate resin E(3)
was contained as the resins contained in the charge-transporting layer.
The configuration of the resins contained in the charge-transporting
layer and the content of the siloxane moiety are shown in Table 7.
Evaluation was made in the same manner as in Example 1. The result is
shown in Table 10. It was found that the formed charge-transporting layer
has no matrix-domain structure.

[0140] The "Component [γ]" in Tables 3 to 6 means the component
β contained in the charge-transporting layer. In the case where the
charge-transporting substances are mixed and used, it means the kinds of
the component γ and another charge-transporting substance and the
mixing ratio thereof. The "Component [α]" in Tables 3 to 6 means
the configuration of the component α. The "Siloxane content A (% by
mass)" in Tables 3 to 6 means the content of the siloxane moiety (% by
mass) in the polycarbonate resin A. The "Component [β]", in Tables 3
to 6 means the configuration of the component β, and any resin
thereof has no siloxane moiety. The "Mixing ratio of component [α]
to component [β]", in Tables 3 to 6 means the mixing ratio of the
component α to the component β (component α/component
β) in the charge-transporting layer. The "Siloxane content B (% by
mass)" in Tables 3 to 6 means the content of siloxane moiety (% by mass)
in the polycarbonate resin A based on the total mass of the resins in the
charge-transporting layer.

[0141] The "Charge-transporting substance" in Table 7 means the
charge-transporting substance contained in the charge-transporting layer.
The proportion represents the mixing ratio of two components γ or
the mixing ratio of component γ/another charge-transporting
substance. The "Resin" in Table 7 means the resin E or the polycarbonate
resin A having a siloxane moiety. The "Siloxane content A (% by mass)" in
Table 7 means the content of the siloxane moiety (% by mass) in the
"Resin". The "Component [β]", in Table 7 means the configuration of
the component β. The "Mixing ratio of resin to component [β]"
in Table 7 means the mixing ratio of the resin E or polycarbonate resin A
to the component β (resin/component β) in the
charge-transporting layer. The "Siloxane content B (% by mass)" in Table
7 means the content of the siloxane moiety (% by mass) in the "Resin E"
based on the total mass of all the resins in the charge-transporting
layer.

[0142] Hereinafter, evaluation results of Examples 1 to 156 and
Comparative Examples 1 to 47 are shown in Tables 8 to 10.

[0143] From the comparison of Examples with Comparative Examples 1 to 12,
if the polycarbonate resin having the siloxane moiety in the
charge-transporting layer has a low siloxane content, a reducing effect
on the contact stress is not sufficiently obtained. This is shown by no
reducing effect on the torque found in the initial torque and the torque
after 2,000 sheets are repeatedly output in the evaluation method. In
Comparative Example 13, if the polycarbonate resin having the siloxane
moiety has a low siloxane content, it is shown that increase in the
content of the siloxane-containing resin in the charge-transporting layer
does not lead to a sufficient relaxing effect on the contact stress.

[0144] From the comparison of Examples with Comparative Examples 14 to 25,
the polycarbonate resin having the siloxane moiety in the
charge-transporting layer has a high siloxane content, the potential
stability in repeating use are remarkably poor. In this case, while the
matrix-domain structure is formed by the polycarbonate resin having the
siloxane moiety, the polycarbonate resin and the charge-transporting
layer excessively contain the siloxane structure, leading to insufficient
compatibility with the charge-transporting substance. For this reason, a
sufficient potential stability in repeating use is not obtained. In
Comparative Example 26, the potential stability in repeating use is
insufficient as well. In the result of Comparative Example 26, the
matrix-domain structure is not formed, and large potential fluctuation
occurs. Namely, in Comparative Examples 14 to 26, it is thought that
compatibility with the charge-transporting substance is insufficient in
the case where the charge-transporting substance and the resin
excessively containing the siloxane structure are contained.

[0145] From the comparison of Examples with Comparative Examples 27 and
28, if the polycarbonate resin having the siloxane moiety in the
charge-transporting layer has a crosslinking structure and does not form
the matrix-domain structure, a relaxing effect on the contact stress is
not sufficiently obtained.

[0146] From the comparison of Examples with Comparative Examples 29 to 34,
the potential stability may be poor in the charge-transporting substance
shown in the present invention even if the matrix-domain structure is
formed using the resin having the siloxane structure. Moreover, the
comparison of Examples with Comparative Examples 29 to 34 shows that use
of the polycarbonate resin according to the present invention improves
the potential stability in repeating use. In this case, it also shows
that in Examples, a sufficient potential stability can be compatible with
a persistent relaxing effect on the contact stress. In Comparative
Examples 29 to 34, the component γ having high compatibility with
the resin in the charge-transporting layer contains a large amount of the
charge-transporting substance in the domain of the siloxane-containing
resin. As a result, the charge-transporting substance is aggregated in
the domain, leading to insufficient potential stability. In Examples,
however, it is thought that the content of the charge-transporting
substance in the domain is reduced because the compatibility of the
component α with the component γ in the present invention is
low. For this reason, it is thought that the content of the
charge-transporting substance in the domain that causes the potential
fluctuation is reduced, and high potential stability is demonstrated. The
results of Comparative Examples 35 to 40 also suggest that the
compatibility of the component α with the component γ
improves the potential stability in repeating use. From the comparison of
Comparative Examples 29 to 34 with Examples, in the case where the
charge-transporting layer containing the components α and γ
according to the present invention is formed, a remarkable suppressing
effect on the potential fluctuation is obtained.

[0147] The comparison of Examples with Comparative Examples 41 to 46 shows
that the potential stability is insufficient if the siloxane moiety has
an aryl group in the case where the matrix-domain structure is formed
using the polycarbonate resin having the siloxane moiety in the
charge-transporting layer. The result of Comparative Example 47 shows
that the potential stability in repeating use is insufficient if the
siloxane moiety has an aryl group even in the case where the
charge-transporting substance and the resin having a proper amount of the
siloxane structure are contained.

[0148] While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is not
limited to the disclosed exemplary embodiments. The scope of the
following claims is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures and functions.

[0149] This application claims the benefit of Japanese Patent Application
No. 2010-231812, filed Oct. 14, 2010, which is hereby incorporated by
reference herein in its entirety.